This invention relates to fuse clips that are soldered to a circuit board to removably receive a flat contact tab of a common automotive fuse, and more particularly to a clip for multi-level circuit boards which is resistant to misalignment and breakage during both the manufacture of the circuit board and the replacement of fuses in the field.
Various types of complex electronic equipment, as for example sprinkler controllers for golf courses, are commonly installed in locations far from electronics supply centers where odd-sized or odd-shaped fuses are likely to be available. Such equipment, particularly in lightning-prone locations, is nevertheless preferably equipped with many fuses so that a lightning strike or short-circuit will disable only a small section of the controlled system rather than shut the controller down entirely. To facilitate the maintenance or repair of such equipment in remote locations, it is desirable that the fuses used in the equipment be common flat automotive fuses which are readily available at any automotive service station.
In order to receive such automotive fuses, printed circuit boards have in the past been equipped with resilient clips into which the flat contact tabs of the fuses can be removably inserted. Examples of such clips and other circuit board contacts are found in U.S. Pat. No. 4,668,866 to Legrady, U.S. Pat. No. 5,624,269 to Kanamori and U.S. Pat. No. 2,869,107 to Engel. Although the contacts of those patents are generally satisfactory for light use, problems arise when they are used in environments using wave-soldered multi-level circuit board assemblies in which fuses interconnect circuits on different levels. Such assemblies require relatively long clips so that a clip mounted on a lower level can protrude high enough above an upper level to securely receive a fuse tab. The extra length of the clip, however, makes it susceptible to tilting when it is inserted into the circuit board prior to soldering. Also, the extra length magnifies the bending stress to which the clip is subjected when a spent fuse is pulled out of the clip, particularly when relatively frequent replacement of the fuses can be expected. In those environments, misalignment of the clip during manufacture, and breakage of the solder connection when the fuse is replaced, can readily occur with adverse results such as intermittent malfunctions.
The fuse clip of this invention substantially reduces clip alignment problems during manufacturing, and solder connection breakage during fuse replacement, by providing a clip which is stabilized by surfaces extending substantially from each face of the clip parallel to the circuit board, so as to maintain the clip vertical prior to soldering and to prevent the clip from tilting during fuse replacement.
The action of the stabilizing surfaces is further enhanced by a three-point triangular leg structure by which the clip is soldered to the circuit board. As a result, the clip of this invention can safely withstand 15-20 fuse replacements as opposed to the 1 or 2 safe replacements common with conventional clips.